This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. (A) OVERALL AIMS The overall aims of this project are to collaborate with the NBCR investigators to: (1) advance mathematical models from the cardiac myocyte level to more integrative whole heart models, and (2) to develop more detailed subcellular cardiac myocyte models at the level of local molecular environments. This will build on the cardiac myocyte cellular models that we are developing in a dynamic feedback with experimental data that is at the core of several grant-funded projects. It will also synergize with multiscale modeling efforts which are a central component of Dr. McCulloch's ongoing projects and of the NBCR Core projects [4A.1A] and [4A.2B].